1. Field of the Invention
The present invention relates to the treatment of snow ski bases to increase lubricity of the ski during skiing. More particularly, the present invention relates to a method of treating sintered base snow skis to increase lubricity of the skis for an extended period without need for frequent retreating.
2. Description of the Prior Art
Sintered base snow skis are commonly employed in both competitive and recreational skiing. Sintered base skis typically have a polymer base, e.g., polyethylene base, which includes a thin polymer layer having pores throughout. This thin polymer layer is laminated in the manufacturing process onto the base of the ski. Such sintered base skis can contain one or more of such polymers combined on the ski base in order to provide optimal performance. As used herein, the term snow skis is intended to include snow skis, snow boards, and boards such as those used on snow mobiles, dog sleds and the like, and includes sintered base skis having one or more than one polymer layer laminated onto the bottom of the ski.
Snow skis, including sintered base skis, are typically waxed to reduce friction and to improve control and speed and accordingly, performance. The smoother the skis run on the snow, the easier they are to control, and the more consistent the skiing will be. Accordingly, ski waxes that impart improved smoothness to the ski as it traverses the snow provide an important safety advantage especially to novice and intermediate level skiers because of the improved responsiveness of the skis. Furthermore, waxing the ski fills the porous openings in the bottom of the ski and covers imperfections in the bottom of the ski surface which may affect the ski's performance.
Conventional and fluorinated waxes are made from fluorinated hydrocarbons. While these waxes generally are believed to not pose environmental concerns, they are typically applied hot and require a modest amount of energy for heating, as well as a source of that energy. Moreover, the hot irons and applicators pose a risk of to injury during use. Typically, optimal performance of waxes are limited to a narrow temperature range, with such ski waxes have an appreciable lifetime on the ski surface of approximately three days.
While waxing ski bases does provide some protection to ski bases with respect to wear and contamination of the ski bases by oils and foreign matter, a hot-waxed ski base will show mechanical wear in as little as two days of use. This type of wear causes the ski base to take on a white fuzzy appearance indicative of abrasion of the ski base surface and the formation of fine hairs of damaged ski base material. Wax cosmetically eliminates this condition by coating the hairs with wax and sticking them down to the base. As the wax wears off, however, the hairs reappear.
The degree of smoothness with which a ski traverses snow may be measured by the ski's lubricity. Waxes previously employed on snow skis have included a lubricity agent which, when applied with the wax to the bottom surface of the ski, increases the lubricity of the ski. One lubricity agent previously employed in ski waxes is a nonionic fluoroaliphatic polymeric ester commercially available under the tradename FC-740 from the Minnesota Mining and Manufacturing Company ("3M"), Industrial Chemical Products Division, St. Paul, Minn. When this agent is employed in a ski wax and applied to the ski surface, the lubricity of the ski is significantly increased when employed at optimal conditions, i.e., ambient temperatures of about 10.degree. F. and below. However, at ambient temperatures above 10.degree. F., the performance of waxes containing this lubricity agent, while still acceptable, are diminished as compared to the performance at 10.degree. F. or below; possibly due to a decrease in lubricity with an increase in temperature.
U.S. Pat. No. 5,114,482 to Terry J. Hertal for WAX FOR USE WITH SINTERED BASE SNOW SKIS describes wax compounds and their use to increase lubricity of sintered base snow skis containing what is characterized as perfluoropolyether diols. These perfluoropolyether diols are functional compounds which include the chemically reactive diols. As disclosed in the Hertal patent, these compounds require a vehicle compatible with the perfluoropolyether diols. Moreover, because they are applied in a wax base, they present the same limitations to use found with ski waxes generally. The use of functional and non-functional perfluoropolyethers as lubricants for magnetic media is known. See, e.g., U.S. Pat. No. 4,526,833 to Burguette, et al., and Caporiccio, "A New Series of Lubricants for Magnetic Recording Media from Bifunctional Perfluoropolyether Derivative", symposium on Memory and Advanced Recording Technologies, San Jose, Calif. (1986).
Attempts have been made to apply liquids to ski bases to increase lubricity. Such attempts, notably with silicone or silicone-based liquids, have not been commercially successful. Silicones have proven to be problematical because of a tendency to migrate. The prevailing view is generally that liquids will not stay on a ski base long enough to increase lubricity during use.
In view of the above, there is a continuing need in competitive and recreational skiing for ski waxes having improved lubricity over those previously available. There is also a continuing need for ski waxes having a broad temperature range for optimal performance and ease of use as well as improved durability which are cost effective.